Don Terrill’s Speed-Talk

Update

Superram flows 280-290 cfm depending on runner
Outside 2 runners that suffered 3+-cfm loss when bolted to base 0 loss

Final volume 194cc
valve job untouched 56cc chamber
kinda wish id done a little more on the intake

Critiques?

int exh
.100 65 62
.200 140 116
.300 200 160
.400 243 193
.500 .276 215
.550 281 224
.600 279 229
.650 278 232
.700 277 236
.750 276 237
.800 276 238

did on 2 different benches posted the stingier one;little disappointed with the intake side but honeslty didnt do much
383 11.5:1 Jones HR 240/243?
what would you pros have done differently sure you can tell by # whats been done

Frankshaft wrote:Until you get it out of your head that you need the low lift to stay, when trying to get it to not stall and go up stairs, YOU WILL NEVER make real power. Sorry to blunt, but, I am flat out am telling you, low lift flow DOES NOT gain low end torque, and everything you do to gain low lift flow, hurts the dynamics of the head that makes real power. I don't care who is telling you otherwise, you simply won't. Cut the appropriate seat, work the port and short turn the way it needs to be to make power, don't mess up the chamber by "unshrouding" to the limits, and you WILL lose low lift flow, period, end of story, and you will make more power. The low lift flow ends up what it is. under .300, not really important, even on lower lift stuff. Not saying you should kill it on purpose but, the things that actually make power, will lose low lift flow.

Not sure how to respond to this but I will try. 1st set of 289 heads I developed I unshrouded to the gasket did lots of chamber shaping and only worked at getting high lift flow to 250 cfm. I did fall short about 238 cfm but when I was developing the ports the low lift fell off a bit but not terrible. 2nd set of 289's I wanted to exceed the flow and velocity with a smaller valve, less chamber deshrouding and shaping. I was hoping to be able to get a much better ssr shape with the smaller intake and lose some airspeed there which would boost the high lift flow. I spent no development time on low lift flow at all. I am hoping to finish these up this weekend and post results. I think the valve job has the biggest effect on low lift flow which is why the 50 + degree seat guys love the high angles. So strange as this may be I agree with this whole paragraph except the low lift boosting torque I have no evidence either way. Thanks, Charlie

Vette, sorry for the thread hijack. Please post up a intake bowl pic! Thanks, Charlie

No icon to upload image from pc or am I missing it?
Only lightly hit one part of the chamber, these things are shaved to the point of no return

cuisinartvette wrote:Friend sent me his to just tune em up some nothing crazy

Numbers picked up nicely everywhere esp .400 and under picke up from .500-550 then stalled which I expected. gains were minimal
Stock AFR valve job

Wanted to keep the head small-
When going for more from .500 up & carry a little further what do you recommend withotu losing downstairs..guy was stuck on .400 and less getting most the work
Havent poured them but doubt if theres 3cc material removed

Share your thoughts, have an idea thought Id pick your brains.

Chasing flow at low lifts isn't the route I'd go.

Figure out what lift the engine will have at what piston position/crank position and that will guide you on what lifts to look at.
Divide the lift into areas like,... BTDC to TDC, TDC to EVC, EVC to peak piston speed - peak piston speed to BDC -BDC to IVC or something along those lines.
Study that and think about where it needs to move a lot of air.

Randy

Thanks Randy gives me lots to think about;always someone to learn from!
Your vortecs were pretty impressive..gonna dig up his cam card may make for more interesting responses

No luck posting a pic?